Re: graphics issues

[Shai Ayal]

On 10/3/06, Quentin Spencer <address@hidden> wrote:
> Joe Koski wrote:
> > on 9/29/06 11:38 AM, John W. Eaton at address@hidden wrote:
> >
> >
> >> On 29-Sep-2006, Shai Ayal wrote:
> >>
> >> | While OpenGL will take care of all the 3D stuff, you still have all
> >> | the "graph" things to take care of -- axes, tics, legends, titles
> >> | etc... All are "trivial" but with many small annoying details (auto
> >> | axes limits and ticks is quite hard IMHO). this is quite a lot of
> >> | work. octplot is under development for more than 2 years (although
> >> | it's not very intensive development) and these things are still far
> >> | from prefect
> >>
> >> I agree that these little details, while each may seem like a simple
> >> problem, add up to a major headache, especially given that the code
> >> already exists in other places (gnuplot, plplot, NCAR graphics, etc.).
> >>
> >> My preference would be to use some existing code if at all possible,
> >> but I don't know where to find something that is relatively easy to
> >> use and not closely tied to a specific plotting package.
> >>
> >> jwe
> >>
> >>
> > A couple of points. I have the post-processor called smokeview for the NIST
> > FDS code (see http://fire.nist.gov/fds/ ). It is an OpenGL application and
> > runs on my Mac (without X11) with 3D displays that I can rotate, change the
> > viewpoint, etc. without the delays or "inertia" that feel when I'm using
> > other applications. Whether a graphics language can run natively on many
> > platforms, including Windows and Macs, should be a major consideration.
> > Apparently OpenGL has that capability, but I'm no expert, so maybe someone
> > can comment on that.
> >
> > Second, the plplot folks have been very active lately, enhancing the
> > package, so maybe plplot should be reevaluated, especially since there is
> > already an octave binding included in the plplot distribution. The plplot
> > folks are adding a wxwidgets driver. Is that tied to X11? The "widgets" in
> > the name sure sounds like X11 is involved. What is the potential impact of
> > wxwidgets on octave? I did play with octave/plplot a year or two ago, and
> > found myself going back to gnuplot. Back then, plplot's main use was for
> > salvaging the graphics on old legacy codes that had outlived their
> > commercial graphics interface (remember DISSPLA?). Maybe now it's different.
> >
>
> The soon to be released gnuplot 4.2 also has a wxWidgets terminal. I've
> tried it and it looks great (anti-aliased fonts and lines). I've been
> ready to give up hope for gnuplot, but this has convinced me to give it
> a second chance. wxwidgets is a cross-platform toolkit that supposedly
> runs natively on each supported platform, so presumably this means X11
> is not required to run it on Mac or Windows.

I fail to see why this new terminal is important other than being
good-looking: even today gnuplot can run natively on X11, win32 &
Aqua. Much more important features to look for would be fine-grained
control on graph appearance. Are this available?

> I tried plplot once or
> twice but I finally gave up on it because it found it unstable on Linux.
>
> With the new gnuplot release, it should not be too difficult to add
> better control over line width, color, etc. It still seems like the
> shortest path to a working backend to the object-graphics frontend. On
> the other hand, the real weakness is that gnuplot is a standalone
> program, rather than a library. The main problem I see with this is that
> data is transfered via file I/O, rather than simply using on data that
> is already in memory. The new version helps a little bit because binary
> data transfer is now supported, but it's still suboptimal for large
> amounts of data. The other big benefit of the new gnuplot is support for
> images, so that the image display routines can be displayed as plots
> with the axes and titles and all.
>
> Anyway, I don't mind dumping gnuplot when something that can replace it
> supports all of the necessary features, but I agree with John that for
> now updating the gnuplot interface seems the quickest way to get what
> people want. I'm happy to be proven wrong by the OpenGL supporters.
>
> -Quentin

The way I see it, the biggest problem with using gnuplot for a backend
is that while it is a very good stand-alone graphing tool ,it is very
bad as a low level plotter (i.e. lines, patches & text).
With gnuplot you can produce very nice and good quality graphs w/o
needing octave at all. The problem starts when you try to control it:
you would have to bend over backwards in order to have gnuplot display
the graphic "document"  that octave wants to display. You can already
see this now -- while high level plots from octave look great on
gnuplot, attempts at low level manipulating are much harder -- e.g.
the automatic_replot=1 problem, multiplots, etc..

Shai